Handling Issues, can the trailing arm flex?


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oldmopars
Posts: 224
Joined: Sun Jun 16, 2013 9:25 am
Location: Selah, Washington
Motorcycle: 1996 GL1500 SE
1989 GL1500 parts bike
1984 GL1200 Aspencade FOR SALE

Handling Issues, can the trailing arm flex?

Post by oldmopars »



So, I have had my 96 SE for a few months now and I have put on about 2000 miles. During this time I have fought with the handling, it just feels bad. So far out of all the bikes I have owned, this is by far the worst handing motorcycle ever. Sadly the list includes a 250 Scooter and a wore out 98 KLR 650 that handled way better.
I was out with some friends riding yesterday and on straights, it is fine. If I am going on a straight road and move the bars back and forth to get it to weave, it feels rock solid. But, when I lean into a corner at any good speed the thing is all over the road like the frame is made out of spaghetti noodles.
As I was riding I paid attention to how it felt and reacted to the bumps in the road, in the curves. As it hits the bumps in the curves the rear is all over the road going left to right. It feels like the two stock shocks are acting differently on the trailing arm and causing it to flex thus causing the wheel to pivot on the axle center line.
Is it possible for the swing arm to flex where one side moves the opposite of the other, or at least not together?
I have a set of Progressive shocks that will go on this winter, I hope they help. However, if the swing arm is cracked/damaged in any way, will the swing arm off the 89 I have fit the 96?



setupmanbob57
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Re: Handling Issues, can the trailing arm flex?

Post by setupmanbob57 »

what shape is your rear tire in ? is it rounded like a new tire or does it have a flat center ? the flat center can make it handle like what you are describing.

oldmopars
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Motorcycle: 1996 GL1500 SE
1989 GL1500 parts bike
1984 GL1200 Aspencade FOR SALE

Re: Handling Issues, can the trailing arm flex?

Post by oldmopars »

The tire is an E3, unknown miles, but is good shape, round profile with slight cupping. I have the pressure at 44psi in the rear, 41psi in the front. I may tray a new tire, but I don't think that is it. I have had worn tires on other bikes and this is 10 times worse.
Imagine if someone cut the swing arm into 2 parts that still held together, now put 2 totally different types of shocks on and go for a ride, that is what this feels like.

setupmanbob57
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Re: Handling Issues, can the trailing arm flex?

Post by setupmanbob57 »

is the swingarm , shocks and final drive tight?

oldmopars
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Motorcycle: 1996 GL1500 SE
1989 GL1500 parts bike
1984 GL1200 Aspencade FOR SALE

Re: Handling Issues, can the trailing arm flex?

Post by oldmopars »

I have not pulled it apart yet. I need to ride it at the end of this month, so I don't want to tear into it too far. However I will take a look and see if the bolts are all tight.
I do see that the swing arms on these bikes get rust in them and it allows flex, then with the different types of shock acting differently on it, it does flex. This may be my issue. the bike is now 22 years old and has 105K miles on it.
I miss my BMW K1200lt right now, it had a cast aluminum single sided swing arm with mono-shock. It handled like a it was on rails no matter the speed or lean.

setupmanbob57
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Re: Handling Issues, can the trailing arm flex?

Post by setupmanbob57 »

when you check the nuts and bolts , check the swingarm bearings also,grab the rear wheel and try to move it from side to side, those are the only things i can think of that may give the problems you are describing , and maybe the steering head bearings , i hope you get it figured out , good luck.

setupmanbob57
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Re: Handling Issues, can the trailing arm flex?

Post by setupmanbob57 »

as far as the swingarm from the 89, it has a different part# then the 96,(89 part# 52100-mn5-p00 96 part# 52100-mam-L40, ) may not fit ? wish i could do more to help.

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MikeB
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Re: Handling Issues, can the trailing arm flex?

Post by MikeB »

OldMopars, I think I would replace that rear tire before I looked much deeper into possible swing arm flexing. I can't say that I have ever heard of that being a problem on the Gold Wing. Of course, there is always the first time and it would probably be attributed to swing arm bearings and not a weak swing arm.

I just replaced my 12,000 mile old set of Dunlop E4's on my GL1800 for the very reason you are talking about. The rear end sometimes felt real squirrely when i was just headed straight down the highway. It was a recent development in the last 3,000 miles or so. I noticed that it did it primarily on grooved pavement. On the asphalt it was not bad at all but most of the highway I have been traveling for the last few months has been concrete. Tar snakes are another mater all together, it is really squirrely on them.

The E4's didn't have that problem early on, only after having several thousand miles on them. From riding mostly highways, the center tread was kind of flat and where it met the sidewalls, there was a slight ridge. Of course, there was a slight bit of shingling or cupping wear on the tire sidewalls as well.

After installing new tires, there is no longer the squirrely feeling I had before. The new tires, I am using Bridgestone Exedra's this time as a test, roll very nicely in the corners. Of course when I used Avon's, which I will probably go back to when these are due for replacement, the bike rolled into the corners very nicely as well.

I've only had the squirrely feeling with the E4's, never on any of the other tires I have used over the last 106,000 miles or so. But that my be because I had always used Avon's prior to this.
MikeB
1998 - GL1500 w/184,500 miles ~ 2017 - GL1800 w/13000 miles
USAF Avionics Communications Tech - 18 Years / Flight Engineer C-130E - C-141B - 6 Years. Retired.
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GlimWas
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Re: Handling Issues, can the trailing arm flex?

Post by GlimWas »

I recognize the handling, same as it was with my '94 a lot of movement in corners with bumps in it. my right shock absorber was worn, despite of the progressive spring around it.
Replaced the whole rear suspension with progressive 416's and all the moving was gone, even with two up. So a test of your shock absorber might be a good idea too
Most motorcycle problems are caused by the nut that connects the handlebars to the saddle

GL1100 '80
GL1200 '87
GL1500 '94

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WingAdmin
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Re: Handling Issues, can the trailing arm flex?

Post by WingAdmin »

The swingarm itself should not flex, and definitely not the two sides of it relative to one another. In fact, the GL1500 as it comes from the factory has a normal spring shock and damper on one side of the swingarm, and the other side has only an air shock used to adjust preload. The bike depends on the stiffness of the swingarm/axle system to balance the two.

I've seen two cases where the swingarm was causing weave or other instability issues. One was on my GL1100, and it was caused by a previous owner who installed the swingarm pivots backwards (left one on right side, right one on left side). Once I installed them correctly and torqued them properly, the problem went away.

The other is swingarms that have started to rust out from the inside, and are beginning to flex and fail. They are hollow, and if they start to corrode from the inside out, they can get weak before they fail altogether.

GL1500 swingarm with rust
GL1500 swingarm with rust


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RockportDave
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Re: Handling Issues, can the trailing arm flex?

Post by RockportDave »

oldmopars wrote:
Sun Oct 14, 2018 7:24 pm
So, I have had my 96 SE for a few months now and I have put on about 2000 miles. During this time I have fought with the handling, it just feels bad. So far out of all the bikes I have owned, this is by far the worst handing motorcycle ever. Sadly the list includes a 250 Scooter and a wore out 98 KLR 650 that handled way better.
I was out with some friends riding yesterday and on straights, it is fine. If I am going on a straight road and move the bars back and forth to get it to weave, it feels rock solid. But, when I lean into a corner at any good speed the thing is all over the road like the frame is made out of spaghetti noodles.
As I was riding I paid attention to how it felt and reacted to the bumps in the road, in the curves. As it hits the bumps in the curves the rear is all over the road going left to right. It feels like the two stock shocks are acting differently on the trailing arm and causing it to flex thus causing the wheel to pivot on the axle center line.
Is it possible for the swing arm to flex where one side moves the opposite of the other, or at least not together?
I have a set of Progressive shocks that will go on this winter, I hope they help. However, if the swing arm is cracked/damaged in any way, will the swing arm off the 89 I have fit the 96?
What psi are you running in the rear shock?
When I got my bike, I was running about 15-20 psi (checked on center stand) and realized that wasn’t enough and the bike was squirrelly in the turns. I played with the air pressure and found 50 psi sitting on the tires with me on it (175 lbs) helped the handling tremendously.
I have G3’s with about 3000 miles on them.
1999 SE with 39000 miles on it now. Also have a Blackwing fork brace.
Dave
1999 GL1500SE 5th Goldwing through the years

oldmopars
Posts: 224
Joined: Sun Jun 16, 2013 9:25 am
Location: Selah, Washington
Motorcycle: 1996 GL1500 SE
1989 GL1500 parts bike
1984 GL1200 Aspencade FOR SALE

Re: Handling Issues, can the trailing arm flex?

Post by oldmopars »

So, I am running 41psi front tire, 44psi rear tire. I have run between 45 and 57psi in the rear shock. I have a Super Brace clone on the front. It looks like it was made by Super Brace for a Trike company, it has their Logo on it.
The weather is turning colder here and the bike is going to be put away for a little while. During the winter months I will rebuild the forks and replace the rear shocks with the Progressives I have.
I hate to replace a tire that is in good shape, but I may have too. I have an Iron But ride planned for June. I will use the tire for that as it is all straight, lot of long highway miles, then I will put on something else, maybe Avon Cobras. I have heard good about the way they handle.



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